From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christophe Leroy Subject: Re: [PATCH v6 07/11] powerpc/kvm/e500: Use functions to track lockless pgtbl walks Date: Thu, 6 Feb 2020 07:18:02 +0100 Message-ID: References: <20200206030900.147032-1-leonardo@linux.ibm.com> <20200206030900.147032-8-leonardo@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200206030900.147032-8-leonardo@linux.ibm.com> Content-Language: fr Sender: linux-kernel-owner@vger.kernel.org To: Leonardo Bras , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Arnd Bergmann , Andrew Morton , "Aneesh Kumar K.V" , Nicholas Piggin , Steven Price , Robin Murphy , Mahesh Salgaonkar , Balbir Singh , Reza Arbab , Thomas Gleixner , Allison Randal , Greg Kroah-Hartman , Mike Rapoport , Michal Suchanek Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org List-Id: linux-arch.vger.kernel.org Le 06/02/2020 à 04:08, Leonardo Bras a écrit : > Applies the new functions used for tracking lockless pgtable walks on > kvmppc_e500_shadow_map(). > > Fixes the place where local_irq_restore() is called: previously, if ptep > was NULL, local_irq_restore() would never be called. > > local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk, > so there is no need to repeat it here. > > Variable that saves the irq mask was renamed from flags to irq_mask so it > doesn't lose meaning now it's not directly passed to local_irq_* functions. > > Signed-off-by: Leonardo Bras > --- > arch/powerpc/kvm/e500_mmu_host.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c > index 425d13806645..3dcf11f77256 100644 > --- a/arch/powerpc/kvm/e500_mmu_host.c > +++ b/arch/powerpc/kvm/e500_mmu_host.c > @@ -336,7 +336,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > pte_t *ptep; > unsigned int wimg = 0; > pgd_t *pgdir; > - unsigned long flags; > + unsigned long irq_mask; > > /* used to check for invalidations in progress */ > mmu_seq = kvm->mmu_notifier_seq; > @@ -473,7 +473,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > * We are holding kvm->mmu_lock so a notifier invalidate > * can't run hence pfn won't change. > */ > - local_irq_save(flags); > + irq_mask = begin_lockless_pgtbl_walk(); > ptep = find_linux_pte(pgdir, hva, NULL, NULL); > if (ptep) { > pte_t pte = READ_ONCE(*ptep); > @@ -481,15 +481,16 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > if (pte_present(pte)) { > wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) & > MAS2_WIMGE_MASK; > - local_irq_restore(flags); > } else { > - local_irq_restore(flags); > + end_lockless_pgtbl_walk(irq_mask); > pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n", > __func__, (long)gfn, pfn); > ret = -EINVAL; > goto out; > } > } > + end_lockless_pgtbl_walk(irq_mask); > + I don't really like unbalanced begin/end. Something like the following would be cleaner: begin_lockless_pgtbl_walk() ptep = find() if (ptep) { pte = READ_ONCE() if (pte_present(pte)) wing= else ret = -EINVAL; } end_lockless_pgtbl_walk() if (ret) { pr_err_rate...() goto out; } > kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg); > > kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize, > Christophe From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v6 07/11] powerpc/kvm/e500: Use functions to track lockless pgtbl walks References: <20200206030900.147032-1-leonardo@linux.ibm.com> <20200206030900.147032-8-leonardo@linux.ibm.com> From: Christophe Leroy Message-ID: Date: Thu, 6 Feb 2020 07:18:02 +0100 MIME-Version: 1.0 In-Reply-To: <20200206030900.147032-8-leonardo@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit To: Leonardo Bras , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Arnd Bergmann , Andrew Morton , "Aneesh Kumar K.V" , Nicholas Piggin , Steven Price , Robin Murphy , Mahesh Salgaonkar , Balbir Singh , Reza Arbab , Thomas Gleixner , Allison Randal , Greg Kroah-Hartman , Mike Rapoport , Michal Suchanek Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org List-ID: Message-ID: <20200206061802.Fodvi0lBep5MRxcSaxseRUE56CQFF0Mv2i49WCyouWg@z> Le 06/02/2020 à 04:08, Leonardo Bras a écrit : > Applies the new functions used for tracking lockless pgtable walks on > kvmppc_e500_shadow_map(). > > Fixes the place where local_irq_restore() is called: previously, if ptep > was NULL, local_irq_restore() would never be called. > > local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk, > so there is no need to repeat it here. > > Variable that saves the irq mask was renamed from flags to irq_mask so it > doesn't lose meaning now it's not directly passed to local_irq_* functions. > > Signed-off-by: Leonardo Bras > --- > arch/powerpc/kvm/e500_mmu_host.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c > index 425d13806645..3dcf11f77256 100644 > --- a/arch/powerpc/kvm/e500_mmu_host.c > +++ b/arch/powerpc/kvm/e500_mmu_host.c > @@ -336,7 +336,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > pte_t *ptep; > unsigned int wimg = 0; > pgd_t *pgdir; > - unsigned long flags; > + unsigned long irq_mask; > > /* used to check for invalidations in progress */ > mmu_seq = kvm->mmu_notifier_seq; > @@ -473,7 +473,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > * We are holding kvm->mmu_lock so a notifier invalidate > * can't run hence pfn won't change. > */ > - local_irq_save(flags); > + irq_mask = begin_lockless_pgtbl_walk(); > ptep = find_linux_pte(pgdir, hva, NULL, NULL); > if (ptep) { > pte_t pte = READ_ONCE(*ptep); > @@ -481,15 +481,16 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, > if (pte_present(pte)) { > wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) & > MAS2_WIMGE_MASK; > - local_irq_restore(flags); > } else { > - local_irq_restore(flags); > + end_lockless_pgtbl_walk(irq_mask); > pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n", > __func__, (long)gfn, pfn); > ret = -EINVAL; > goto out; > } > } > + end_lockless_pgtbl_walk(irq_mask); > + I don't really like unbalanced begin/end. Something like the following would be cleaner: begin_lockless_pgtbl_walk() ptep = find() if (ptep) { pte = READ_ONCE() if (pte_present(pte)) wing= else ret = -EINVAL; } end_lockless_pgtbl_walk() if (ret) { pr_err_rate...() goto out; } > kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg); > > kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize, > Christophe